Enhanced hydrogen evolution performance of Co/CoP in electrolysis of water by interfacial regulation of crystal plane orientation

Abstract

Modulating the heterojunction interface is an effective way to improve the electrocatalytic efficiency of water electrolysis, and the metal centers with preferred crystal plane orientation offer the potential to enhance the interfacial charge transfer and electrode reaction kinetics. In this study, a Co/CoP modified hydrogen evolution electrode with selective exposure of the metal-centered Co(002) crystal face was prepared using a one-step electrodeposition method by adjusting the P/Co molar ratio. Results demonstrate that the preferential orientation of Co(002) crystal face in Co/CoP leads to an increased electrochemical active surface area, significantly reduced interfacial impedance and Tafel slope. Moreover, it brings the d-band center closer to the Fermi level, which is thermodynamically favorable for hydrogen evolution reaction (HER). Under optimized conditions, Co/CoP exhibits overpotentials of 85 mV and 183 mV at 10 mA cm−2 and 100 mA cm−2, respectively. After long-term and cyclic stability tests, no significant activity decay is observed, demonstrating excellent hydrogen evolution activity and cyclic stability.